Possibly they may have noticed that the sticky leaves of the butterwort (Pinguicula vulgaris) are sometimes strongly incurved.
If, observing these matters, they have given them but a passing thought; have failed to see the relation, or apprehend the motives of the phenomena; and are surprised some day by learning that they point to one of the most wonderful discoveries of modern biology—they need reproach themselves with no exceptional heedlessness or obtuseness, for they have the illustrious company of most of the famous botanists from Linnæus down to those of the present generation.
Some attention has recently been called to the carnivorous habits of what Dr. Hooker calls "our brother-organisms—plants," by the appearance in different scientific periodicals of some brief note, or paper, by occasional observers; and more generally by Prof. Gray's papers which appeared in the Nation, April, 1874, pp. 216, 232, in which he announced some of the facts that had been communicated by Mr. Darwin and others. Some of these statements must, it should be said, be modified in the light of later observations.
It has turned out, as so often it does, that some of the more obvious observations and conclusions were made and drawn long ago, and recorded only to be overlooked and forgotten. The subject has a history running back a century or more. It is of more than common interest, and has been well told by Dr. Joseph Hooker, in his address to the department of Zoölogy and Botany, British Association, Belfast, August, 1874. Much condensed, it is as follows:
Dionæa.—About 1768, Ellis, a well-known English naturalist, sent to Linnæus a drawing of a plant, to which he gave the poetical name of Dionæa. "The plant," wrote Ellis, "shows that Nature may have some views toward its nourishment in forming the upper joint of its leaf like a machine to catch food; upon the middle of this lies the bait for the unhappy insect that becomes its prey. Many minute red glands that cover its surface tempt the animal to taste them; and, the instant these tender parts are irritated by its feet, the two lobes rise up, grasp it fast, lock the rows of spines together, and squeeze it to death. And further, lest the strong efforts for life in the creature, just taken, should serve to disengage it, three small spines are fixed near the middle of each lobe, among the glands, that effectually put an end to its struggles. Nor do the lobes ever open again while the dead animal continues there. It is nevertheless certain that the plant cannot distinguish an animal from a vegetable or mineral substance; for, if we introduce a straw or pin between the lobes, it will grasp it fully as fast as if it were an insect."
This account, substantially correct, but erroneous in some particulars, led Linnæus to declare that, though he had seen and examined no small number of plants, he had never met with so wonderful a phenomenon. He was, however, too sagacious to accept Ellis's account of the coup-de-grâce which the insects received from the three stiff
